Between nucleotides that are right next to each other- Covalent bond between 3' to 5'

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Differences between DNA and RNA

RNA is single stranded and DNA is double stranded

RNA has Uracil to replace DNA's Thymine

RNA has ribose sugar (2'C has OH) and DNA has deoxyribose sugar (2'C has H)

Chromatid

Replicated chromosome strand

Chromatin

DNA + Proteins

Beads on a string.

Chromosomal DNA

Nucleosome: core histones H2A, H2B, H3, and H4 (octamer)

Liner Histone H1 and non-histone chromosomal proteins

30 nm condensed

10 nm decondensed via salt

DNA replication, DNA repair, Transcription, Recombination

Genetic

Coded within the nucleotide sequence of the genome.

Mendelian inheritance of genes from parent to progeny

Epigentic

Coded outside the nucleotide sequence

a.) DNA methylation: genes can be inherited with Me marks

b.) Chromatin Modification: Histone marks can be inherited

Heterochromatin

Chromatin is more highly compact. Silencing.

Telomeres and centromeres

Spreads if not stopped.

Euchromatin

Chromatin is more extended. Gene activation.

Chromatin Remodeling Complex

Protein machine that can move the nucleosomes around. Can open up a whole region of chromatin or move away. They use ATP hydrolysis to move chromatin/ move histones. Move nucleosome to get access to DNA.

Genetic Inheritance

When DNA sequences are copied quickly and correctly.

Effects how we look, act, behave, etc.

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Epigenetic Inheritance

Histones and their modifications must also be replicated.

Each daughter chromosome will inherit about half of its parent's collection of modified histones. The remaining stretches of DNA receive newly synthesized, not yet modified histones. Proteins that recognize a particular modification can bind to the chromatin and catalyze the formation of the same modification on the new histones. Restores parental modification pattern and allows inheritance of parental chromatin structure.

DNA polymerase

Synthesizes new DNA using one of the old strands as a template. This enzyme catalyzes the addition of nucleotides to the 3' end of a growing DNA strand by forming a phosphodiester bond between this end and the 5'- phosphate group of the incoming nucleotide.

Where DNA is first opened and marked by a particular sequence of nucleotides. Initiator proteins will initiate the complex with the help of DNA helicase (separates strands).

Lagging Strand DNA Replication Cascade

DNA Primase synthesizes new RNA primer.

RNA Primer is started on the new strand. DNA polymerase continues where RNA Primer left off to finish the DNA fragment (until it hits the next RNA primer).

RNase (nuclease) will digest the RNA parts and DNA polymerase will repair, meaning make the RNA into DNA.

DNA ligase comes in and links the Okazaki fragments together.

Telomerase

Replicates the ends of chromosomes.

-If DNA primase wants to add the DNA primer, cant replicate the end of the strand like it can in the middle of the strand. If it could, nuclease would digest

-Requires a length of template RNA that is beyond the DNA that is copied. Telomerase adds a series of repeats of a DNA sequence to the 3' end of the template, which then allows the lagging strand to be completed by DNA polymerase. This is done with RNA sequence complementary to DNA repeat seq.

Huntington's Disease

A model of triplet repeat expansions. Mutation in DNA replication- making more repeats. If have more than CAG 42 repeats. Neurological disorder.

Late onset genetic disorder (40s and 50s)

Transmitted as a vertical, autosomal dominant allele

Severe depression, cognitive defeats and chorea (movement disorder)

Progressive neurodegeneration that is ultimately fatal

If understood the slips and uncorrect replication, then maybe could help

Thymine Dimer

Chemical lesions caused by UV radiation.

-Repaired by nucleotide excision repair (NER) proteins that remove the specific proteins that are wrong and add the correct bases.

Xeroderma Pigmentosa

Cannot repair thymine dimers because of an inherited defective gene for mutation in NER genes and proteins. NER disruption

-People will develop severe skin lesions, skin cancer because of the accumulation of thymine dimers in cells that are exposed to sunlight and the consequent mutations that arise in the cells that contain them.

Nonhomologous End Joining

Double stranded break in the DNA perhaps by xray. Broken ends are recognized by cell and gamma H2AX recognizes the double stranded breaks to process them via nuclease. Will reattach the two ends together. Deletions of nucleotides at the repair sites. Leaves a gap while homologous doesn’t. Not as accurate as homologous. Lose whatever you had originally.

RNA polymerase

The enzyme that synthesizes RNA copy of template strand in the 5’ to 3’ direction

-Doesn't need a primer to start synthesizing.

-Signals in DNA tells it where to start (promotors) and finish (terminals).

mRNA

Code for proteins

rRNA

Form the core of the ribosome and catalyze protein synthesis

miRNA

Regulate gene expression

tRNA

Serve as adaptors between mRNA and amino acids during protein synthesis